Design And Experiment Of Seed Metering Device For Rapeseed Based On Seeding Frequency Feedback

For solving the problem that the seed metering device does not realize real-time feedback adjustment according to the seeding frequency,which leads to unstable seeding quantity and affects seeding quality.In this paper,a seed metering device for rapeseed based on seeding frequency feedback control of seeding information was designed,the seeding frequency can be measured,adjusted and controlled.This device can ensures high seeding quality of rapeseed and provides technical support for precision seeding in small fields.Details of the research are as follows.(1)The seed metering device for rapeseed based on seeding frequency feedback was designed and optimized,and it achieves a more stable precision seeding work of the device.The seed metering device for rapeseed based on seeding frequency feedback consists of a spiral-tube metering device,a small grain size seed sensing module,a detection and control module,a drive module and a fixing module.In order to orderly pass all seeds through the sensing area of the small grain size seed sensing module,the structure of the seed guide tube was designed.This seed guide tube can match the sensor module.The design of the seed metering device for rapeseed based on seeding frequency feedback was optimized to ensure stable operation.The results showed that when the machine at normal working speed,the seeding frequency of device range was 10.2～50.2Hz,which met the working requirements.(2)The signal processing system of seed metering device for rapeseed based on seeding frequency feedback was designed to realize the functions of seed detection,planter working speed acquisition and motor speed control.It lays the foundation for control system design.Based on the determination of the sensing structure parameters of the sensing module,the signal processing system was designed by amplitude frequency analysis of the sensor signal.The seed counting program was designed by using the seed signal processed by the detection circuit as the interrupt source of the microcontroller.And carried out the detection accuracy test.The results showed that the detection accuracy error of sensing module was less than 1.30% at the counting instrument seeding frequency of8.0～20.4Hz.Further test was carried out using a real-time detectable seed metering device for rapeseed,the results showed that the accuracy was greater than or equal to 87.05% at the seed metering device for rapeseed seeding frequency of 10.1～60.3Hz.Based on the analysis of the detection principle and seeding amount detection accuracy test results,a compensation model for the accuracy of the seeding amount detection was constructed and validated.The test results was that the detection accuracy of device was greater than or equal to 98.75% in the range of 60.4Hz seeding frequency.The improved detection accuracy provides the basis for the subsequent precise control of seeding frequency.(3)The PD control algorithm-based seeding frequency control system of seed metering device for rapeseed was designed,and the detected seeding frequency was used as the control system input to achieve precise control of seeding frequency.The hardware structure of the seeding device control system consists of a metal dome array,OLED screen,motor driver,Hall rotating speed measurement sensor,DC speed reduction motor,singlechip microcomputer controller,information conditioning circuit and n RF wireless transceiver,laser emission module,silicon light receiver and DC power supply.The relationship between seeding frequency of device and the rotational speed was measured,and the results showed that the linear correlation between the seeding frequency and rotational speed was 0.99 in the rotational speed range of 34～200r/min.The theoretical seeding frequency was obtained from the input seeding information and the acquired forward speed.The difference between the detected seeding frequency and the theoretical seeding frequency determined by the controller was used as input to the PD controller,which made the decision on the control amount and drives the motor to perform the corresponding seeding work.(4)The bench test and field test of seed metering device were conducted to verify the working performance of the device.Under different rotation speed of horizontal disc conditions,the bench test results was that the C.V.of seeding quantity stability was less than 1.16%,which met the requirement of rape seeding quality.The result of field test was that in case of different forward speeds of tractor,the seeding quantity detection accuracy of seed device for rapeseed was no lower than 98.75%,the seeding amount error rate was no more than 2.55% and the C.V.of seeding quantity stability was less than 0.98%.The seed metering device for rapeseed based on seeding frequency feedback meet the requirements of industry standard.